Roller ridge expanding tool

ABSTRACT

An expanding tool is provided which utilizes low friction means to expand tubular structures, for example, electrode elements for electronic air filters. The low friction means, in the illustrated embodiment, comprises a plurality of roller wheels arranged to provide tube expansion at spaced intervals about the tube. The particular construction utilized enables the radial expansion force exerted during tube expansion, that is, the force of the roller against the tube, to be balanced by the reaction force between the rollers themselves. Consequently, the only force required to push the expanding tool is that necessary to overcome the friction force of the rollers.

United States Patent [191 Wightmanet al.

[451 Mar. 19, 1974 ROLLER RIDGE EXPANDING TOOL Assignee: Emerson Electric Co., St. Louis County, Mo.

Filed: Feb. 25, 1972 Appl. No.: 229,457

US. Cl. 72/393, 72/113 Int. Cl B2ld 41/02 Field of Search 72/113, 117, 208, 209, 72/225, 237, 370, 393

References Cited UNITED STATES PATENTS 3.640.115 2/1972 Duncan 72/393 Primary Examiner-Charles W. Lanham Assistant Examiner-M. J. Keenan Attorney, Agent, or F irmPolster and Polster [5 7] ABSTRACT An expanding tool is provided which utilizes low friction means to expand tubular structures, for example. electrode elements for electronic air filters. The low friction means. in the illustrated embodiment. comprises a plurality of roller wheels; arranged to provide tube expansion at spaced intervals about the tube. The particular construction utilized enables the radial expansion force exerted during tube expansion, that is, the force of the roller against the tube, to be balanced by the reaction force between the rollers themselves. Consequently, the only force required to push the expanding tool is that necessary to overcome the friction force of the rollers.

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sum 1 or 2 FIG. 9.

PAIENIEDIARIQ m4 3797391 7 FIG. 14.

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ROLLER RIDGE EXPANDING TOOL BACKGROUND OF THE INVENTION This invention relates to expanding means and in particular, to a novel roller expander. While the expanding means is described with particular emphasis on its use in the construction of electronic air filter cells, those skilled in the art will recognize the wide applicability of the concept of our invention to other tube expanding uses and systems.

In the construction of electronic air filter cells, it is conventional to fabricate a series of plates having a plurality of openings in them. For example, it is conventional to have a large diameter and a small diameter opening adjacent one another on each end of a substantially rectangular plate. Plates are placed alternately so that a channel through a series of plates is provided comprising sequential large and small diameter openings. Thereafter, at least two electrodes for the cell are inserted through the channels. The electrodes conventionally are tubular structures constructed from a material capable of conducting electricity. Aluminum electrodes work well from both a cost and a handling ease standpoint. Prior to expansion, the electrodes easily pass the channel defined by the alternate size openings. When the electrodes are expanded, they engage alternate plates along and about the small diameter openings in those plates. The expansion process conventionally is all that is required to form the electrodes and plates into a single unit containing a plurality of parallel plates, each plate being engaged by an electrode. By providing the proper distance between alternate plates, it becomes possible, after expansion, to electrically charge sequential plates to opposite polarities by applying voltage to the electrodes. The use of these oppositely charged plates is well known in the art of electronic air filters.

A number of expanding tools capable of ensuring electrode-plate engagement are provided inthe art. These expanding tools conventionally are bullet shaped masses which are pushed or pulled through the tubular electrode. The bullet shape engages the tubular structure along its circumference. Consequently, a consider able frictional force must be overcome in order to force the expander tool through the tubular structure. Because of the high frictional force encountered, it is common, in the expanding process, to include the step of applying lubricant along the internal diameter of the electrode structure. The lubricant, heretofore, has been essential before the expander could be forced through the electrodes, particularly through thin wall electrodes desirable because of their lower cost. Application of lubricant in turn requires a lubricant: removal step in the construction process. Each additional step further increases product cost.

The forces required to expand the tubular structure present other problems. As indicated above, it is desirable, both from cost and operational aspects, to utilize thin walled electrodes in cell construction. The wall thickness of the electrode previously has been restricted by the force required to expand the electrode. That is, with conventional expanders, the force required to push or pull the expander through the electrode is such as to distort the tube axially during the expandingprocess. The axial distortion is detrimental in cell construction and electrode length must be corrected where that length has been changed after expansion. Correction is an additional, time consuming and costly step in the construction process.

Our invention materially reduces the force required to run an expander tool through the electrode. Consequently, axial electrode distortion is materially reduced. Lubrication of the internal electrode no longer a is required. Electronic air filter cell construction is expedited while product cost is reduced.

One of the objects of this invention is to provide an improved expanding tool.

- Another object of this invention is to provide an ex- SUMMARY OF THE INVENTION In accordance with this invention, generally stated, an expanding tool is provided which exhibits low friction characteristics during the expansion process.

In the preferred embodiment, the expanding tool has a plurality of rollers extending radially outwardly from it which are arranged about thebody of the expander. The rollers are arranged so as to balance the radial expansion force between the rollers.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings,

FIG. 1 is a view in perspective of one illustrative embodiment' of expanding tool of this'invention;

FIG. 2is a view in side elevation of a first component for expanding tool illustrated in FIG. 1;

FIG. 3 is a view in side elevation ofa second component for the expanding tool shown in FIG. 1;

FIG. 4 is a sectional view taken along theline 4-4 of FIG. 3;

FIG. 5 is a view in side elevation, partly broken away, of a third component for the expanding tool illustrated in FIG. 1; v

FIG. 6 is a view in side elevation, partly broken away, of the expanding tool illustrated in FIG. 1;

FIG. 7 is an enlarged sectional view taken along the line 7-7 of FIG. 6;

13-13 of FIG. 12; and

FIG. 14 is an enlarged sectional view taken along the area 1414 of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, reference numeral 1 indicates the expanding tool of this invention. Tool 1, in the embodiment illustrated, includes a rear portion 2, a center part 3, and a lead section 4, illustrated in FIGS. 2, 3 and 5 respectively.

Rear portion 2, as best illustrated in FIG. 2, includes a generally cylindrical outer shell 5. Shell 5 has a first end 6 and a second end 7. Shell 5 has an axial opening 8 in it, running from the end 6 for a predetermined distance within the shell 5. Opening 8 is designed to receive a pusher means for driving expanding tool 1, not shown, which is attached to the expander tool 1 by and along the opening 8. In the embodiment illustrated, the opening 8 narrows along a distalend 9 within the shell 5 and includes a plurality of threads 10 along its circumference which aid in attaching the above mentioned push means to the tool 1. Other connection means may be used to interconnect the push means and the tool 1.

End 7 of rear portion 2 has an axial opening 11 in it, running from the end 7 for a predetermined distance within the shell 5. The opening 11 is intended to receive a thin piece of wire 12 the purpose of which is described in detail hereinafter. Wire 12 may be any of a variety of wire available commercially. For example, common piano wire works well. A plurality of openings 13 extend radially outwardly through the shell 5, near the end 7. In the embodiment illustrated, rear portion 2 has four openings 13 extending through it, spaced annularly about the shell 5 at ninety degree intervals. The openings 13 resemble rectangular openings in plan, as is best illustrated in FIG. 2. It also may be there observed that the axial opening 11 and the openings 13 meet within the shell 5, so that a channel exists between pairs of openings 13.

Shell 5 forms a male connector portion 14 along the second end 7. That is, the external diameter of the shell 5 is reduced along a series of bevel edges 15 until the desired reduced diameter for the connector 14 is achieved.

Center part 3, illustrated in FIG. 3, generally is cylindrical in shape having a body part 16 delimited by a connection'end l7 and a connector end 18. Connection end 17 has an opening 19 in it, corresponding in shape to the connector 14 of rear portion 2. Connection end 17 is designed to receive the connector 14 of rear portion 2 in a close slip fit. The opening 19 has a flared annular lip 20 about it, formed by the body part 16, the purpose of which is described in detail hereinafter. Various methods for fastening rear portion 2 and center part 3 are available. We prefer use of an epoxy adhesive in conjunction with a slip fit for this interconnection.

Body part 16 has a plurality of openings 21 extending radially outwardly through it. In the particular embodiment illustrated, center part 3 has four openings 21 in it, spaced annularly about body part 16 at 90 intervals. Body part 16 also has an axial opening 22 extending from end 17 to and communicating with opening 19. Opening 22 is designed to align with opening 11 in the intermounted positions of the elements of expanding tool 1 illustrated in FIG. 1.

Connector end 18 is similar in design to the connector 14. That is, the end 18 has a reduced diameter along a connector 23 formed by a plurality of bevel edges 24.

Lead section 4, illustrated in FIG. 5, includes a generally cylindrical body 25 having a connection end 26 and a lead end 27. Body 25, in the embodiment illustrated, is a solid structure in cross section, with the exception of the connection end 26. Body 25 has'an opening'28 in it along the connection end 26. Opening 28 conforms to the silhouette of connection end 18 of center part 3 and is designed to accept that part in a close slip fit. Again, we prefer an epoxy joint for the interconnection, although other connection means, for example, interlocking threads, may be used. Opening 28 has an annular lip 29 about it, which is similar in construction and use as the lip 20. The function of lip 29 is described in detail hereinafter. Lead end 27 has a bullet nose formed by tapering the body 25 to form a frustum 30.

The expanding function, as later described, actually is accomplished through the use of a plurality of roller wheels 31, an illustrative example of which is shown in FIGS. 8 and 9. Each roller 31 is a cylindrical section having a first diameter 32 which is expanded along a beveled, annular edge 33 to an enlarged second diameter 34. The edges 33 provide force transmitting surfaces, the purpose of which are later described in detail. The enlarged diameter portion 34 defines an expanding rim 35 which in fact is the portion of the tool 1 that accomplishes actual expansion.

' The openings 13 and 21 are similar to each other and are designed to be receptacles for the roller wheels 31. It may be observed in FIG. 4 that the openings 21 extend radially through the body part 16. The design, construction and function of the openings 13 are identical to the openings 21, and only the openings 21 are described in detail. The openings 21 generally are rectangular and extend from and through body part 16, as is best illustrated in FIG. 4. The rollers 31, prior to the joining of the rear portion 2, center part 3, and lead section 4, are inserted in the openings 21 in a free, friction fit. The openings 22 and 1 l are designed to receive a predetermined length of wire 12. Placement of the wire 12 and rollers 31 result in the cross-section structure shown in FIG. 7. It there is observed that the diameter of the tool 1 is less than that defined by the rollerwire 12 combination so that the expanding ridge 35 of each roller 31 extends radially outwardly beyond the diameter of tool 1. It also is evident that the edges 33 of adjacent rollers 31 abut one another when the rollers are positioned as shown in FIG. 7.

Construction of the tool of this invention is simple. The parts are fabricated separately and then connected to form the embodiment shown in FIG. 1. Thus, rear portion 2, is utilized as a base to build the-tool. Wire 12 is inserted within opening 11 and four rollers 31 are placed in the opening 13 about shell 5. The rollers 31 are held within openings 13 in a loose friction fit. Center part 3 is then mounted, via connector 14, to rear portion 2. Some care must be taken during the positioning as it is desirable, although not mandatory, to have rollers 31 spaced annularly about the diameter of the tool 1 in approximately forty five degree increments. An alignment aid, for example, a split hair line,

may be 'used to ensure proper positioning, if desired. I

The connector 14 fits the opening 19 in a close slip fit. Preferably, epoxy adhesive or similar substance is utilized to bind the parts permanently. As previously indiable in a close slip fit. Again, an epoxy adhesive is used to bind them permanently. Where epoxy is utilized, the now integral tool 1 is allowed to cure prior to use.

As is best illustrated in FIG. 14, opening 28 has an annular lip 29 about it. The lips 29 and are identical in purpose and function and only one lipis shown in the drawings and discussed in detail. Lip 29 forms a flared end for the opening 28. It may be observed, by noting the relative position of openings 13 and 21 and with respect to the connectors 14 and 23 and the openings 19 and 28, that the lips 29 and 20 will close a portion of the openings 13 and 21 respectively in the intermounted position. This overlap is enlarged and illustrated in FIG. 14. As there demonstrated, lip 29 includes an upper edge 36 and an inner edge designated as wear pad 37. Wear pad 37 abuts the rollers 31 and locks them within their respective openings 13 and 21. Additionally, the wear pads 37 provide a bearing surface for rotation of the rollers 31.

The tool 1 is intended for use in the construction of electronic air cleaner cells indicated generally by numeral 38in FIG. 10. The cell 38 conventionally comprises a plurality of spaced, parallel plates 39. The plates 39 generally are rectangular having a plurality of openings 40 in them. The particular pattern for the Numerous variations, within the scope of the appended claims, will occur to those skilled in the art in light of the foregoing description and accompanying drawings. While the tool of our invention was described in relation to an electronic air filter cell, those skilled in the art will recognize the practicality of our invention in condenser units for air conditioners and the like among its many other uses. The configuration of the tool may be'varied. For example, the length, diameter or design of the tool may be changed. While the tool 1 was described as cylindrical, other designs may be utiopenings is important in the operation of the cell 38 best observed in FIG. 11. Alternate plates thereafter may be positioned to provide a channel for electrode 41 insertion through the plurality of plates. By expanding the electrode 41, alternate plates in the cell 38 can be fixed to a particular electrode. The tool of our invention is particularly well suitedfor expanding the electrodes. FIG. 10 illustrates the situation where the tool 1 is beginning the expansion process. Although only a single tool 1 is illustrated, those skilled in the art will recognize the desirability and the practicality of simultaneous insertion by a plurality of tools into the various electrodes. It is observed in FIG. 12 that the expanding ridge 35, upon entrance of the electrode 41,

forces the tubular structure of electrode 41 radially,

is displaced, it contacts the wire 12. The wire 12 pre-- vents further displacement. Rather, each roller maintains its relationship with the others in each set, along the beveled edges 33. This construction provides extremely low friction electrode expansion, as only minimal force is required to push the tool 1 through the electrode 41. r

lized. A hexagonal shape, for example, also works well. The number of rollers 31 may be varied or their position with relation to the tool 1 and to each other may be changed. For example, two or three rollers 31 may be positioned to distribute the expansion force rather than the four roller combination illustrated. Other roller combinations will be apparent to those skilled in the art from the previous discussion. The design of the roller 31 in itself .may be altered. Thus, the thickness of the roller may be reduced or increased, depending on particular application demands. While we have found the use of wire 12 within the tool 1 of our invention the preferable design, test units have been constructed without the wire 12 and the use of the wire is not required in all embodiments of our invention. We find, 7

however, that the wire 12 acts in the same way with respect to the rollers 31 as the separator of a ball bearing acts with respect to theballs. The method of attaching the components of our invention to one another may be altered. While we prefer the use of an epoxy adhesive, other connection means, for example, threaded intermount s, may be utilized. Likewise, while the opening8 which is used to connect the tool 1. to its pusher means was described as threaded, other forms of interconnection are compatible with the broader aspects of our invention. These variations are merely illustrative.

Having thus described the invention, what is claimed and desired to be secured by LettersPatent is:

1. In an expanding instrument including an elongated body adapted for insertion in a tube requiring expansion, the improvement comprising a first pair of expanding means mounted for rotation with respect to said body and positioned spacially 180 apart, a second pair of expanding means mounted forrotation' with respect to said body and positioned spacially 180 apart,

said first and said second pairs of expanding means being placed about said body so as to provide an expanding means at approximately increments, said pairs of expanding means adapted to exert pressure against one another during expansion, each of said expandingmeans further comprising a roller having a first end and a second end, each of said ends having a beveled edge, the beveled edges of one pair of said expanding means being contiguous with the beveled edges of the other pair-of said expanding means in said rotation mounted position, and a wire strand placed within said elongated body between said first and said second pairs of expanding means. v

2. An expanding instrument comprising: an elongated body, said elongated body including a rear portion, a center part, and a lead section interconnected to form saidelongated body, said rear portion and said center part having a plurality of openings in them, said center part and said lead section each delimiting an annular lip along an end thereof adapted to restrict a part of said openings in said rear portion and said center part respectively;

a first set of expanders mounted to said body, extending radially outwardly therefrom and rotatable with respect thereto, said expanders being adapted to exert pressure against one another during an expansion process, said expanders comprising first and second pairs of rollers mounted for rotation with respect to said body in said opening plurality of said rear portion and positioned spacially 180 apart; and i a second set of expanders mounted to said body, ex-

tending radially outwardly therefrom and rotatable with respect thereto, said expanders being adapted to exert pressure against one another during an expansion process, said expanders comprising first and second pairs of rollers mounted for rotation with respect to said body in said opening plurality of said center part and positioned spacially 180 apart, each of said second expanders lying in a plane other than the plane of each of said first expanders.

3. The instrument of claim 2 wherein said lead section narrows at one end.

4. An expanding instrument comprising:

an elongated body, said elongated body including a rear portion, a center part, and a lead section which are interconnected to form said elongated body, said rear portion including a section having a first end and a second end, one of said first and said second ends forming a connector, said rear part having a plurality of openings in it near said connector, said center part having a first end and a second end, one of said first and said second ends forming a connector and the other of said first and said second ends forming a connection for said connector of said rear portion, said center part connection end having a lip formed about it which restricts a portion of said openings in said rear portion, said center part having a plurality of openings in it near said center part connector end;

first expanding means, said first expanding means comprising at least one pair of rollers mounted for rotation with respect to said body in said opening plurality of said rear part, positioned spacially 180 apart; and

second expanding means, said second expanding means comprising at least one pair of rollers mounted for rotation with respect to said body in said opening plurality of said center part, positioned spacially 180 apart, said second expanding means lying in a plane other than the plane of said first expanding means.

5. The instrument of claim 4 wherein said lead section comprises an elongated part having a connection end, said connection end adapted for intermounting with said connector of said center part, said connection end having a lip portion which restricts a portion of said opening plurality of said center part in the intermounted position of said lead section and said center part.

6. The instrument of claim 5 further characterized by a wire strand extending between said first and said second expanding means.

7. A device for providing ridge expansion of a tubular structure, comprising:

a body structure, said body structure including a first portion and a second portion intermountable with said first portion, said first portion having a connector end and at least two openings extending radially through it, near said connector end, said second portion having a connection end for receiving said connector end of said first portion, said connection end having a lip about it; and

a first pair of expanders rotatably mounted in said body structure and extending outwardly therefrom through said openings in said first part, said first pair of expanders being at least partially restricted from radial movement by the lip of said second portion, said expanders being adapted to exert pressure against one another during expansion of said tubular structure.

8. The device of claim 7 wherein said second portion of said body structure includes a connector end opposite said connection end, said second portion having at least two openings extending radially through it,-near said connector end, said body structure being further characterized by a third portion intermountable with said second portion, said third portion having a connec- 10. The device of claim 9 wherein each of said first and said second portions have a plurality of openings in it, each of said openings having an expander extending radially outwardly from it, each of said expanders comprising a roller having a first and a second end, each of said ends having a beveled edge, the beveled edges of the expanders mounted in respective ones of said first and said second portion being contiguous with one another on at least one of said first and said second ends. 1

l1. The'device of claim 10 further characterized by a wire strand placed in said body structure between said first and said second pairs of expanders.

12. In an expanding instrument including an elongated body having an external diameter, adapted for insertion in a tube requiring expansion, said tube hav-' ing an internal diameter larger than said external diameter, the improvement comprising first means for ridge expanding said tube outwardly so as to define at least two ridges along an external surface of said tube, said ridge expanding means comprising a first pair of rollers mounted for rotation with respect to said body and positioned spacially apart so as to be capable of exerting pressure against one another during expansion, the diameter of said expanding instrument along a longitudinal cross-section through said rollers being larger than the internal diameter of said tube.

13. The improvement of claim 12 further characterized by second means for ridge expanding said tube outwardly, said ridge expanding means comprising a second pair of rollers mounted for rotation with respect to said body and positioned spacially 180 apart, said first and said second ridge expanding means being placed about said body so as to provide an expanding means at approximately 90 increments, each of said expanding means adapted to exert pressure against one another during expansion, the external diameter of said expanding instrument taken through either of said first and said second ridge expanding means being larger than the internal diameter of said tube.

14. The improvement of claim 13 wherein eachof said expanding means comprises a roller having a first end and a second end, each of said ends having a beveled edge, the beveled edge of one pair of said expanding means being contiguous with the beveled edges of the other pair of said expanding means in said rotation mounted position on at least one of said first and said second ends.

15. The improvement of claim 14 further characterized by a wire strand placed within said elongated body between said first and said second expanding means.

16. A tube expanding instrument for ridge expanding a tubular structure with an internal diameter and an external diameter, comprising:

an elongated body having a diameter less than the internal diameter of said tube; and a first set of expanders mounted to said body, extending radially outwardly therefrom, and rotatable with respect thereto, said expanders and said body defining an effective diameter for said expanding instrument, said effective diameter of said expanding instrument being greater than the internal diameter of said tube such that insertion of said expanding instrument in said tubular structure causes the external diameter of said tube to be expanded in an amount equal approximately to the difference between said internal tube diameter and said effective diameter of said expanding instrument along a track corresponding to the passage of said expanding instrument. 

1. In an expanding instrument including an elongated body adapted for insertion in a tube requiring expansion, the improvement comprising a first pair of expanding means mounted for rotation with respect to said body and positioned spacially 180* apart, a second pair of expanding means mounted for rotation with respect to said body and positioned spacially 180* apart, said first and said second pairs of expanding means being placed about said body so as to provide an expanding means at approximately 90* increments, said pairs of expanding means adapted to exert pressure against one another during expansion, each of said expanding means further comprising a roller having a first end and a second end, each of said ends having a beveled edge, the beveled edges of one pair of said expanding means being contiguous with the beveled edges of the other pair of said expanding means in said rotation mounted position, and a wire strand placed within said elongated body between said first and said second pairs of expanding means.
 2. An expanding instrument comprising: an elongated body, said elongated body including a rear portion, a center part, and a lead section interconnected to form said elongated body, said rear portion and said center part having a plurality of openings in them, said center part and said lead section each delimiting an annular lip along an end thereof adapted to restrict a part of said openings in said rear portion and said center part respectively; a first set of expanders mounted to said body, extending radially outwardly therefrom and rotatable with respect thereto, said expanders being adapted to exert pressure against one another during an expansion process, said expanders comprising first and second pairs of rollers mounted for rotation with respect to said body in said opening plurality of said rear portion and positioned spacially 180* apart; and a second set of expanders mounted to said body, extending radially outwardly therefrom and rotatable with respect thereto, said expanders being adapted to exert pressure against one another during an expansion process, said expanders comprising first and second pairs of rollers mounted for rotation with respect to said body in said opening plurality of said center part and positioned spacially 180* apart, each of said second expanders lying in a plane other than the plane of each of said first expanders.
 3. The instrument of claim 2 wherein said lead section narrows at one end.
 4. An expanding instrument comprising: an elongated body, said elongated body including a rear portion, a center part, and a lead section which are interconnected to form said elongated body, said rear portion including a section having a first end and a second end, one of said first and said second ends forming a connector, said rear part having a plurality of openings in it near said connector, said center part having a first end and a second end, one of said first and said second ends forming a connector and the other of said first and said second ends forming a connection for said connector of said rear portion, said center part connection end having a lip formed about it which restricts a portion of said openings in said rear portion, said center part having a plurality of openings in it near said center part connector end; first expanding means, said first expanding means comprising at least one pair of rollers mounted for rotation with respect to said body in said opening plurality of said rear part, positioned spacially 180* apart; and second expanding means, said second expanding means comprising at least one pair of rollers moUnted for rotation with respect to said body in said opening plurality of said center part, positioned spacially 180* apart, said second expanding means lying in a plane other than the plane of said first expanding means.
 5. The instrument of claim 4 wherein said lead section comprises an elongated part having a connection end, said connection end adapted for intermounting with said connector of said center part, said connection end having a lip portion which restricts a portion of said opening plurality of said center part in the intermounted position of said lead section and said center part.
 6. The instrument of claim 5 further characterized by a wire strand extending between said first and said second expanding means.
 7. A device for providing ridge expansion of a tubular structure, comprising: a body structure, said body structure including a first portion and a second portion intermountable with said first portion, said first portion having a connector end and at least two openings extending radially through it, near said connector end, said second portion having a connection end for receiving said connector end of said first portion, said connection end having a lip about it; and a first pair of expanders rotatably mounted in said body structure and extending outwardly therefrom through said openings in said first part, said first pair of expanders being at least partially restricted from radial movement by the lip of said second portion, said expanders being adapted to exert pressure against one another during expansion of said tubular structure.
 8. The device of claim 7 wherein said second portion of said body structure includes a connector end opposite said connection end, said second portion having at least two openings extending radially through it, near said connector end, said body structure being further characterized by a third portion intermountable with said second portion, said third portion having a connection end for receiving said connector end of said second portion, said connection end of said third portion having a lip about it.
 9. The device of claim 8 further characterized by a second pair of expanders rotatably mounted in said body structure and extending outwardly therefrom through said openings in said second portion, said second pair of expanders being at least partially restricted from radial movement by the lip of said third portion.
 10. The device of claim 9 wherein each of said first and said second portions have a plurality of openings in it, each of said openings having an expander extending radially outwardly from it, each of said expanders comprising a roller having a first and a second end, each of said ends having a beveled edge, the beveled edges of the expanders mounted in respective ones of said first and said second portion being contiguous with one another on at least one of said first and said second ends.
 11. The device of claim 10 further characterized by a wire strand placed in said body structure between said first and said second pairs of expanders.
 12. In an expanding instrument including an elongated body having an external diameter, adapted for insertion in a tube requiring expansion, said tube having an internal diameter larger than said external diameter, the improvement comprising first means for ridge expanding said tube outwardly so as to define at least two ridges along an external surface of said tube, said ridge expanding means comprising a first pair of rollers mounted for rotation with respect to said body and positioned spacially 180* apart so as to be capable of exerting pressure against one another during expansion, the diameter of said expanding instrument along a longitudinal cross-section through said rollers being larger than the internal diameter of said tube.
 13. The improvement of claim 12 further characterized by second means for ridge expanding said tube outwardly, said ridge expanding means comprising a second pair of rollers mounted for rotation with respect to said body and positioned spacially 180* apart, said first and said second ridge expanding means being placed about said body so as to provide an expanding means at approximately 90* increments, each of said expanding means adapted to exert pressure against one another during expansion, the external diameter of said expanding instrument taken through either of said first and said second ridge expanding means being larger than the internal diameter of said tube.
 14. The improvement of claim 13 wherein each of said expanding means comprises a roller having a first end and a second end, each of said ends having a beveled edge, the beveled edge of one pair of said expanding means being contiguous with the beveled edges of the other pair of said expanding means in said rotation mounted position on at least one of said first and said second ends.
 15. The improvement of claim 14 further characterized by a wire strand placed within said elongated body between said first and said second expanding means.
 16. A tube expanding instrument for ridge expanding a tubular structure with an internal diameter and an external diameter, comprising: an elongated body having a diameter less than the internal diameter of said tube; and a first set of expanders mounted to said body, extending radially outwardly therefrom, and rotatable with respect thereto, said expanders and said body defining an effective diameter for said expanding instrument, said effective diameter of said expanding instrument being greater than the internal diameter of said tube such that insertion of said expanding instrument in said tubular structure causes the external diameter of said tube to be expanded in an amount equal approximately to the difference between said internal tube diameter and said effective diameter of said expanding instrument along a track corresponding to the passage of said expanding instrument. 